Governor-magnet.



T. FARMER, JR.

GOVERNOR MAGNET.

APPLICATION FILED SEPT- s. ma.

1,217,928. Patented Mar. 6, 1917.

UNITED STATES PATENT OFFICE.

THOMAS FARMER, TIL, OF NEW YORK, N. Y., ASSIGNOR TO CONSOLIDATED GAR-HEATING .COMPANY, OF ALBANY, NEW YORK, A CORPORATION OF WEST VIRGINIA.

GOVERNOR-MAGNET.

To all whom it may concern:

Be it known that I, THOMAS FARMEB, Jr., a citizen of the United States, residing at New York city, county and State of New York, have invented certain new and useful Improvements -in Governor-Magnets, the following being a full, clear, and exact disclosure of the one form 'of my invention which I at present deem preferable.

For a detailed description of the present form of my invention, reference may be had to the following specification and to the accompanying drawing, which illustrate my invention, wherein Figure 1 shows my invention diagrammatically;

Figs. 2, 3, 4 and 5 show the different conditions of its operation.

My invention relates to a device for-opening and closing an electric circuit containing a governor magnet for an electric switch. For example, the said circuit may be automatically closed by a thermostat when the temperature to which the thermostat is exposed reaches a specified value and, for illustration, I have shown it in connection with such .a thermostatic arrangement wherein the magnet when energized closes the circuit of the electric heaters in a railway car or other apartment. I intend to use my device in any situations requiring the occasional and more or less frequent closure of the magnet circuit such as in air-brake systems, water-level control by a float and similar cases.

Referring to the drawing, S represents a switch that is to be automatically opened or closed at certain periods. In this case, it is to open and close the circuit of an electric heater comprising heater coils H H H H, and H which, when the circuit is closed,

. are, operated by the current from the trolley T of an electric railway line having a voltage ofsay 600with respect to the ground. K is a switch-operating magnet and C is a thermostat which, at a given temperature, will cause a contact thereon. to engage .contact d to apply the trolley voltage to magnet K which has one of its terminals connected to said contact. (I and, of course, will break it engagement therewith at a higher temperature. The opposite terminals of magnet-coil K is connected to an intermediate Specification of Letters Patent.

Application filed September 5, 1913. Serial No. 788,240.

resistance of 20 ohms, so that, when-switch S is closed, a current of six amperes will flow through the heater, each section thereof consuming 120 volts, so that, the point f being at 600 volts, the point wwill be at 480 volts. When, on the other hand, the switch S is open and thermostat C closed, the point a will be at onl about 54 volts. Hence at the instant of c osure of the thermostat C, the magnet K will be subject to a potential difference of about 546 volts, and will immediately act to close switch S, but when it has closed the said switch, the said magnet K receives a potential difference of only 120 volts. The resistance R is of such high amount that it does not have any practical effect in diverting current around the-magnet K and has been neglected in the fore,

\ going figures, but while it does not practically decrease either the initial power or the retaining power of the magnet K, yet it is of importance when the thermostat opens its contactsas the 40,000 ohms resistance R is then in series with the 800 ohms magnet coil K across a potential of 120 volts and the current flow is so small through coil K that it cannot hold in its core any longer and the switch S opens.

The resistance R thenv absorbs the inductive effect caused bythe opening of the magnet circuit andprevents an are at the contact d, it being also observed that the thermostat breaks contact at (Z while the switch S is still closed, the voltage that is thus broken being only 120.

By means of. the device described above I am enabled to use but a single magnet for switch S, which small current will be sufiicient to retain the switch closed but not enough to heat the magnet coils, which can therefore be kept in circuit indefinitely. I am also able to have this single magnet actuate the switch S directly in contrast to the usual practice of using it merely as a relay to govern a more powerful switch-operating magnet or motor. The resistance R is also short-circuited while switch S and thermo- .stat C are both closed and so does not need the costly construction required for a resistance generating heat which has to be radiated away.

Fig. 2 represents the conditions when the thermostat contacts are fully open and the switch S is also open. -Fig. 3 represents the conditions when the contact is closed at (Z but before the magnet has closed the switch. Fig. 4 represents the conditions when the switch S is closed, and Fig. 5 represents the conditions when the contacts are open at (Z, but before the switch S has opened.

llt will be understood that the figures I have given represent but those suitable for one situation wherein the voltage is at one given value. For other situations the figures will be altered according to the engineering requirements.

It will also be manifest that T operate the governonmagnet K by applying thereto a voltage that is determined by the resistance sections H H and H which at that timeg'educe by only 54 volts the line voltage of 600 applied to the magnet so that the magnet receives the comparatively high Voltage of 546. Subsequently I reduce this high voltage on the magnet by introducing additional current into the said resistance sections to raise the voltage-drop thereof. If this additional current is the current in the circuit controlled by switch S, as is the case in the embodiment of my invention exemplified herein, the voltage drop in said resistance-sections will be raised from 54 to 480, and that will reduce correspondingly the voltage applied to the magnet K. That is, it will now have but 120 volts applied to it instead of 546 volts. Finally I open the contacts (Z at a time when magnet K is shunted by the resistance-section H and the very high resistance R in series with H,. The resistance-section H is in the circuit through which the additional current aforesaid is introduced into sections H H. H, and H to raise the voltage-drop therein. Hence the section is subjected to that additional current and gives a voltage-drop dependent on the magnitude of that current. Resistance R is, on the other hand, in parallel with the said additional-current circuit and its voltagedrop is independent of the said additional current.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with a resistance and a source of current, of a switch interposed between the source of current and said resistance, a governor magnet for operating said switch, said magnet being interposed between the source of. current and said resistance and grounded through the latter at an intermediate point, and contacts between said magnet and the source of current and operable to close the circuit directly to the magnet.

2. A. governor-magnet and contacts therefor combined with a switch controlled by the magnet, a resistance controlled by the switch, a connection between the magnet coil and an intermediate point in said resistance, and a high resistance shunting said magnet.

A governor magnet and contacts therefor in combinatlon with a res1stance,a swltch controlling the supply of current to said resistance, said switch being opened and closed by said magnet, and connections be tween one terminal of the magnet and one of said contacts. a portion of said resistance being interposed between the other terminal of said magnet and the ground.

4. Av governor magnet and contacts there for combined with a switch having a movable member controlled by said magnet, a connection between one terminal of the magnet and one of said contacts, a resistance between the other terminal of the magnet and the ground, and a resistance having one terminal connected with the movable member of said switch and the other terminalv ground d through thefirst resistance at the point oi connection of the magnet therewith.

5. A governor-magnet and contacts therefor, combined with a switch controlled by said magnet, a connection between one mag net terminal and one of said contacts, a rc sistance between the opposite magnet terminal and the switch, a high resistance shunting said magnet and said resistance, and a resistance between the last mentioned magnet terminal and the ground.

6. A governor-magnet circuit comprising two parallel branches, one branch containing a magnet coil and a resistance, the other branch containing a high resistance, a contact for the magnet connected to the said parallel branches on one side, and a switch controlled by said magnet and. connected to the said parallel branches on the other side.

In witness whereof I have hereunto set my hand, before two subscribing witnesses, this 4th day of September, 1913.

THOMAS FARMER, JR.

Witnesses:

FRANK DANNIIAUSER, L. T. S. ERISMAN. 

